netdev - [PATCH v2 bpf 4/5] bpf: add missing rcu_dereference() in bpf_prog_array_delete

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Message-ID: <20180713194114.2711-4-guro@fb.com>
Date:   Fri, 13 Jul 2018 12:41:13 -0700
From:   Roman Gushchin <guro@...com>
To:     <netdev@...r.kernel.org>
CC:     <linux-kernel@...r.kernel.org>, <kernel-team@...com>,
        Roman Gushchin <guro@...com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>
Subject: [PATCH v2 bpf 4/5] bpf: add missing rcu_dereference() in bpf_prog_array_delete_safe()

There is a missing rcu_dereference() in bpf_prog_array_delete_safe().
The progs argument is a __rcu pointer, so dereferencing should be
performed using rcu_dereference(), as, for example, in
bpf_prog_array_length().

This patch helps to remove the following sparse warning:
kernel/bpf/core.c:1629:34: warning: incorrect type in initializer (different address spaces)

Fixes: 324bda9e6c5a ("bpf: multi program support for cgroup+bpf")
Signed-off-by: Roman Gushchin <guro@...com>
Cc: Alexei Starovoitov <ast@...nel.org>
Cc: Daniel Borkmann <daniel@...earbox.net>
---
 kernel/bpf/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index fdf961f70deb..722ae6913dc0 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -1625,7 +1625,7 @@ int bpf_prog_array_copy_to_user(struct bpf_prog_array __rcu *progs,
 void bpf_prog_array_delete_safe(struct bpf_prog_array __rcu *progs,
 				struct bpf_prog *old_prog)
 {
-	struct bpf_prog **prog = progs->progs;
+	struct bpf_prog **prog = rcu_dereference(progs)->progs;
 
 	for (; *prog; prog++)
 		if (*prog == old_prog) {
-- 
2.14.4